Abstract 1324: IL-36 signalling enhances a pro-tumorigenic phenotype in colon cancer cells with cancer cell growth restricted by administration of the IL-36R antagonist

Abstract Background & Aims: The IL-1 subfamily, IL-36, is increasingly being implicated as a potent cytokine family involved in chronic inflammatory conditions such as psoriasis and IBD. Recent work has also suggested IL-36 cytokines may act as a potential adjuvant in immunotherapy regimens to augment the anti-cancer immune response. Given the pluripotent nature of IL-1 cytokines and the relationship between inflammation and tumorigenesis, we investigated the effects of IL-36 signalling in colorectal cancer (CRC). Methods: IL-36 family expression in CRC progression was investigated by the NCBI GEO transcriptomic database, and then by immunohistochemistry (IHC) and qRT-PCR. Pro-tumorigenic properties such as cancer cell migration, invasion and proliferation were investigated in 2D and 3D models. In vivo models were performed using Balb-c mice which were subcutaneously inoculated with CT26 cells and treated with IP injections of recombinant IL-36R agonists (IL-36α, β, γ) or antagonist (IL-36RN). Tumour tissues were excised and studied by flow cytometry and IHC analysis. Additionally, CRISPR-Cas9 mediated IL-36R KO CT26 cells were generated and subcutaneously injected into Balb-c mice, with changes in tumour growth and immune cell infiltrate investigated. Results: IL-36R expression was shown to significantly increase with stage of disease in the adenoma-carcinoma sequence, including distant metastases. Additionally, expression of all family members was increased in tumour tissue relative to adjacent normal tissue in a separate colon cancer cohort. In vitro IL-36R signalling on cancer cells augmented a pro-tumorigenic phenotype by induction of pro-tumorigenic cytokines/chemokine production, increased cellular migration, invasion and proliferation of tumour cells. In vivo inhibition of IL-36R signalling by both administration of recombinant IL-36RN and through deletion of the IL-36R gene in CT26 cells, resulted in a significant reduction in tumour growth. This reduction was associated with a significant decrease in tumour cell proliferation, as well as an increase in CD8+ T cell infiltrate in IL-36R KO groups. Of note, administration of IL-36R agonists also resulted in reduced tumour growth, albeit to a lesser extent, associated with an increase in CD4+ and CD8+ T cell infiltration. Conclusions: This data indicates that IL-36 family members, similar to other IL-1 family members, have dual functions in colon cancer. In addition, this data suggests that targeting IL-36R signalling may be a useful targeted therapy for CRC patients with IL-36R+ tumour cells. Citation Format: Kevin J. Baker, Charlotte O'Donnell, Micheal O'Riordain, Elizabeth Brint, Maura Bendix, Aileen Houston. IL-36 signalling enhances a pro-tumorigenic phenotype in colon cancer cells with cancer cell growth restricted by administration of the IL-36R antagonist [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1324.